diff --git a/lib/outputcomponents.php b/lib/outputcomponents.php
index c5c204674af..16f1fe27f9a 100644
--- a/lib/outputcomponents.php
+++ b/lib/outputcomponents.php
@@ -270,7 +270,7 @@ class user_picture implements renderable {
      * @return moodle_url
      */
     public function get_url(moodle_page $page, renderer_base $renderer = null) {
-        global $CFG, $FULLME;
+        global $CFG;
 
         if (is_null($renderer)) {
             $renderer = $page->get_renderer('core');
@@ -329,7 +329,7 @@ class user_picture implements renderable {
             // Build a gravatar URL with what we know.
             // If the currently requested page is https then we'll return an
             // https gravatar page.
-            if (strpos($FULLME, 'https://') === 0) {
+            if (strpos($CFG->httpswwwroot, 'https:') === 0) {
                 $imageurl = new moodle_url("https://secure.gravatar.com/avatar/{$md5}", array('s' => $size, 'd' => $imageurl->out(false)));
             } else {
                 $imageurl = new moodle_url("http://www.gravatar.com/avatar/{$md5}", array('s' => $size, 'd' => $imageurl->out(false)));
diff --git a/lib/pagelib.php b/lib/pagelib.php
index f01e74ceaad..aafe23a79dc 100644
--- a/lib/pagelib.php
+++ b/lib/pagelib.php
@@ -1185,6 +1185,8 @@ class moodle_page {
         }
 
         // now the real test and redirect!
+        // NOTE: do NOT use this test for detection of https on current page because this code is not compatible with SSL proxies,
+        //       instead use strpos($CFG->httpswwwroot, 'https:') === 0
         if (strpos($FULLME, 'https:') !== 0) {
             // this may lead to infinite redirect on misconfigured sites, in that case use $CFG->loginhttps=0; in /config.php
             redirect($this->_url);
diff --git a/lib/setup.php b/lib/setup.php
index 2b51b1bd4ea..2f0f1e4f1fa 100644
--- a/lib/setup.php
+++ b/lib/setup.php
@@ -341,6 +341,10 @@ global $MCACHE;
 
 /**
  * Full script path including all params, slash arguments, scheme and host.
+ *
+ * Note: Do NOT use for getting of current page URL or detection of https,
+ * instead use $PAGE->url or strpos($CFG->httpswwwroot, 'https:') === 0
+ *
  * @global string $FULLME
  * @name $FULLME
  */
diff --git a/mod/lti/locallib.php b/mod/lti/locallib.php
index 53425a3d144..74f0276046f 100644
--- a/mod/lti/locallib.php
+++ b/mod/lti/locallib.php
@@ -1127,8 +1127,8 @@ function lti_get_launch_container($lti, $toolconfig) {
 }
 
 function lti_request_is_using_ssl() {
-    global $FULLME;
-    return (stripos($FULLME, 'https://') === 0);
+    global $CFG;
+    return (stripos($CFG->httpswwwroot, 'https://') === 0);
 }
 
 function lti_ensure_url_is_https($url) {